DESCRIPTION (provided by investigator): This is an investigation of the effects of disinhibition on early risk for substance use. Disinhibition is a complex construct, and it is proposed that separating its constituent parts and examining their relationship to each other and to putative precursors of early substance use will elucidate one specific pathway, an antisocial pathway, to substance abuse. The proposed high-risk sample will include 11-13 year-olds (50 percent diagnosed with both ADHD and either ODD or CD and 50 percent without a DSM-IV diagnosis). Three core aspects of disinhibition will be assessed: (1) Autonomic reactivity as assessed by reactivity to reward and extinction during a continuous performance task, (2) Behavior as assessed by deficits in passive avoidance during a go/no-go discrimination learning task, and (3) Attention as assessed by a bias to attend to reward relative to punishment cues exhibited during a target detection. Cardiac reactivity to reward, electrodermal hyporeactivity to extinction, deficits in passive avoidance, and a relative bias to attend to reward versus punishment cues are expected to covary. These aspects of disinhibition are considered distal risk factors for early substance use. Accordingly, a mediational model is proposed such that core aspects of disinhibition will predict disruptive behavior problems, which in turn will predict affiliations with deviant peers (a proximal risk factor for early substance use). Multiple reporter data (parent and child) will be used to assess disruptive behavior and peer affiliations. The proposed project integrates a model of individual differences with socialization theory using a developmental framework to understand risk for early substance use involvement. It will provide data that will inform etiological models of adolescent substance use, specifically with regard to an antisocial pathway.